Purpose Ipilimumab and radiation therapy (RT) are standard treatments for advanced melanoma; preclinical models suggest the potential for synergy. However, limited clinical information exists regarding safety and optimal timing of the combination. Methods and Materials We reviewed the records of consecutive patients with unresectable stage 3 or 4 melanoma treated with ipilimumab. Patients were categorized as having received RT or not. Differences were estimated between these 2 cohorts. Results We identified 88 patients treated with ipilimumab. At baseline, the ipilimumab-plus-RT group (n=44) had more unfavorable characteristics. Despite this, overall survival, progression-free survival, and both immune-related and non–immune-related toxicity were not statistically different ( P =.67). Patients who received ipilimumab before RT had an increased duration of irradiated tumor response compared with patients receiving ipilimumab after RT (74.7% vs 44.8% at 12 months; P =.01, log-rank test). In addition, patients receiving ablative RT had non–statistically significantly improved median overall survival (19.6 vs 10.2 months), as well as 6-month (95.1% vs 72.7%) and 12-month (79.7% vs 48.5%) survival rates, compared with those treated with conventionally fractionated RT. Conclusions We found that both ablative and conventionally fractionated RT can be safely administered with ipilimumab without a clinically apparent increase in toxicity. Patients who received ipilimumab before RT had an increased duration of irradiated tumor response.
